Initial tear-testing apparatus



Oct. 25, 1932.

c. B. THWING l INITIAL TEAR TESTING APPARATUS Filed July 16, 1929 5 Sheets-Sheet l N w v f\Z 'mung umnnml Ilm llllllllllllllllnlllIIIIIIIIIIIIIIIIIIIIIHI Oct. 25, 1932.. C, B, THWlNG 1,884,388

INITIAL TEAR TESTING APPARATUS Filed July 16, 1929 5 Sheets-Sheet 2 0d 25, 1932- c. B. THWING INITIAL TEAR TESTING APPARATUS Filed July 16, 1929 5 SheetS-Sheet Oct. 25, 1932, Q B, THWING 1,884,388

INITIAL TEAR TESTING APPARATUS Filed July 16, 1929 5 Sheets-Sheet 4 Oct. 25, 1932.

A c. B. THwlNG INITIAL'TEAR TESTING APPARATUS F'iled July 16, 1929 5 Sheets-Sheet reo Fatented Oct. 25,l 1932 CHARLES B. TIIWING, or iIIILAnnLrIIIA,

INSTRUMENT COMPANY, or PHILADELPHIA, PENNSYLVANIA, A CORPORATION or PENNSYLVANIA Application filed yJuly 16,

This invention relates to tear-testing apparatus and more particularly to nan apparatus for testing the initial tear of paper, cardboard or other sheet material.

An `important object of the invention'is the provision in a construction of this character of an arrangement such that a simple" but accurate indication l of the torsional strain applied at the moment of initial tear maybe provided. f

A still 'further object of the invention is to provide apparatus of this character in which the construction is such thatV the graduations of a recording. scale maybe spaced in a manner providing larger spaces at those periods Vat' which initial tear ordinarily occurs so that 1a much more accurate indicationcanbev had than is usual. I y' still further obj ect of thei'nvention'is the provision of apparatus of this character in which the indication is maintained after recession of the drive shaft during the tearing operation so that there'isxno necessityfor constant attention to the scale.

.A still further object of the inventionis the production of apparatus of this character which may be readily and cheaply produced, in which the paper .may be readily inserted for the testing operation, and which will be durable and efficient in service.

These and other objects I attain ,by the construction shown in the accompanying d'rawi K Referring now more particularly to .the

ings, wherein for thepurpose of illustration I have shown a preferred embodiment ofwmy invention and wherein: y

Fig. 1 is a side elevation of a: tear-testing machine constructed in accordance with my invention;

Fig. 2 is a plan view thereof;

. Fig.3 is a section on line 3-3 of Fig. 1; I"

Fig. 5 lis an end elevation with the pointer and dialremoved; and v v Fig. 6 is a section on line 6-6 of Fig. 4.

drawings, the numeralv 10 designates a suitable' base supported, for a purpose hereinafter to appear, upon adjustable ,legs 11. Af

These legs kare at present yshown as in the n form of bolts directed through the base.

PATENT OFFICE TENNsYLvANIA, AssIGNoR To TII'wING INITIAL TEAR-TESTINGAISIABATUS maf seriai No. 378,691.

Arising from thisbase are opposed standards 12 and 13 having at their upper ends bearings-14Cr and 15 receiving shafts 16 and 17 respectively. Adjacent ends of shafts 16 and V17 are each provided with a jaw head 18 comprising a iiXed jaw 19 rigid to the shaft and a movable jaw element 20adjustinent of which toward the associated fixed jaw ele'- nientgi's accomplished by ineans of a capstan serew`21, or the like. These jaw elements are adapted to receive therebetween a sheet of paper P which is to be tested for initial tear.

Means are provided for rotating shaft 16 including avreducing gear train 22 and a shaft 23 which is mounted in bearings 211 carriedV by the standards and is provided adj acentto the outer face ofy standard 13 with a cranlr`25. A friction brake 26 is associated with-'shaft 23 `and more particularly with the :hub 27 ofthe cranlr handle 25, in order that l`the action of this shaft 'may be smooth. This is necessary due to the fact that a jerky operation of shaft 23 would result in sudden strains being placed `upon the paperxsheet AMP whichA is tested and these strains would have a tendency to cause tearingin advance l nism hereinafter described. V

In the present instance this brake is illus tratedas comprising the arm 28 pivoted upon the outer face of standard 13 as at 29 and having associated therewith adjusting screw k30 by means of which the free end of the arm 28 may` be urged toward the hub 27. VThe face of the free end of thearin co-acting with the hub may have brake material or any other n .suitable friction material applied thereto. Fig. 4 isV an end elevation of the machine;

to an indicator gear `34 which is rotatably kmounted upon a shaft 35. Shaft 35 is rotatably mounted in and projects outwardly from'the outer face of standard 13 and has securedtheretoadisc 36 having an outstanding peg 37 arranged in the path of a similar' 'lull peg 38 carried by gear 34. The outer end of shaft 35 passes through a dial 39 and is equipped with pointer 40.

It will be obvious that if some means are provided for resisting rotation of shaft 17, with a constantly increasing force, inter 40 will be moved by rotation of the shaft through the gear train and gear 34 and engagement of pegs 37 and 38 until the aper P begins to tear, at which time the orces resisting rotation of shaft 17 will tend to reverse the rotation of this shaft for, as is well known, after initial tear continued tearing requires considerably less force. This reverse rotation of shaft'l7 will cause peg 38 to leave peg 37 with the. result that pointer 40 will remain in its furthest advanced position and will provide the indication of the poundage with which the paper resisted the tearing strains if dial 39 be properly graduated. s

It will also be obvious that ordinary papers upon which tests would be made would nearly all tend to tear at a relatively low poundage and furthermore where the tearing poundage is low it is essntial that a much more accurate record thereof be obtained than is necessary where it is high. Accordingly, in the production of the machine 1t is essential to practicability that some means be provided which will enable a minutely accurate record of low poundages to be obtained. This might of course be accomplished by varying the extent of movement of pointer 40 through the gear train but this is impractical as the range over which tearing tests must be made is airly large. Y

l secure to shaft 17 at the inner end thereof a pendulum 41 and it will be obvious that by employi this pendulum a relatively low weight initiall applied to the pendulum will cause a consi erable movement thereof, the force with which the pendulum resists rotation increasing with the sine of the angle through which the shaft is rotated This pendulum has means for .securing test Weights 42 thereto so that the actual testing capacities of the machine may be considerably varied.

In order to provide for initial settling of the machine I secure to the -base 10 pointer 43 co-acting with an index line 44 upon the pendulum` and b adjusting screws 11 to vary the angle o base 10 the index line 44 can be brought into proper relation to this pointer. A stop 45 is rovided to prevent movement of the pendu um 41 in one direction and to check rotation of the pendulum during return movements after a tearing-test.

In use of the apparatus the sheet to be -tested is inserted between the jaws of the respective heads, the jaws tightened and shaft 23 rotated. The rotation of shaft 16 thus provided is transmitted through the tothe shaft 17 with corresponding shafts movement of the indicator pointer as hereinbefore described. When the tearing point of the sheet is reached and initial tear starts the pendulum is unsupported or its tendency to return rotation will be resisted by a lesser force with the result that pendulum 41 will stu't Aits return travel reversing the direction of rotation of shaft 17. Rotation of shaft 35 being suitably frictionally resisted, as for example 'by friction brake 46, pointer 40 will remain in its furtherest advanced position to Lprovide the desired indication.

s the construction illustrated is obviously but one of many arrangements of the apparatus which is possible, I do not wish to be understood as limiting myself thereto except as hereinafter claime I claim:

1. In a tear-testi machine, opposedaxial- 1y aligned inde'pen ently rotatable shafts, means at adjacent ends of said shafts for clamping thereto the ends of a sheet to be torn sai clamping means being aligned in the general direction of the axes of the shafts and having their adjacent ends s ced, means for positively rotating one o said means resisting rotation of the other of said shafts and means for registering rotation of the last-named shaft.

2. In a tear-testing machine, means engaging one end of an edge of a sheet for Vrotatir the same about an axis paralleling said e ge of the sheet, means e aging the opposite end of said edge of the gleet for resisting rotation thereof with a force increasing with the angular displacement of the sheet and means for registering the extent through which the sheet is rotated at the moment of initial tear.

3. In a tear-testing machine, normally aligned clampin means ada ted to receive opposite ends o an edge ofp a sheet to he tested, said clam ing means being rotatable about an axis su stantially paralleling said edge, means for positivelyV rotating one of said ing means and means resisting rotation of -the other of the said clam ing means with a force increasing with tlie angular .displacement thereof, the last-named means constantly tending to; return the clamping means to its normalposition and means for indicating vthe furthest extent of rotation of the last-named clamping means.

4. In a tear-testing machine, op ed standards, shafts rotatable thereln, camp-- ing heads carried by adjacent ends of said shafts and disposed in end to end relation, said clamping heads having their adjacent ends spaced, means for positively rotating one of the shafts, a pendulum secured to the other of the shafts and means for indicating angular displacement of the pendulum.

'5. In a tear-testing machine, rotatable clamping means arranged in aligned end `to end relation and adapted to engage opposite ends of an edge of a sheet to be tested, means for rotating one of said clamping means about an axis paralleling said edge of the sheet, means normally maintaining the other of the clamping means in a predetermined position and resisting movement of the lastnamed clamping means from said position With a force increasing with the sine of the angle through which it is rotated and an indicator means operatively connected with the lastnamed clamping means and registering the extent of movement of the lastnamed clamping means from its normal position.

6. In a tear-testing machine, opposed standards, shafts rotatable therein, clamping heads carried by adjacent ends of the shafts, means for positively rotating one of said shafts, a pendulum secured to the other of the shafts, an indicator, mea-ns positively connecting the pendulum shaft and the indicator during movement of the pendulum shaft from a normal position and disconnectv ing said shaft and indicator during return movement of the shaft and means for frictionally resisting rotation of the indicator.

7. A device as claimed in claim 6 wherein the means for rotating the first-named shaft include a third shaft, and means are provided for frictionally resisting rotation of the third shaft.

CHARLES B. THWING. 

